Spacer is a dielectric formed alongside the gate electrode of a metal-oxide-semiconductor field effect transistor (MOSFET) device. In addition to protect the gate electrode, the spacer is also configured to allow the formation of source/drain regions and/or lightly doped drain (LDD).
In MOSFET devices, leakage currents need to be reduced in order to save power consumption. One of the leakage components in MOSFET devices is gate-induced drain leakage (GIDL), which is caused by trap assisted band-to-band tunneling at the surface of the drain region where the gate electrode overlaps the drain region. GIDL is sensitive to many factors such as the thickness of gate dielectric, the dopant concentration of drain region, and the applied gate voltage, as well as the width of spacer. As the complexity and application of integrated circuit increase, there are more challenges to suppress leakage current among different MOSFET devices.